I have a newer blog post about MDS, that provides a much simpler solution. Please check it before reading further.

This is a part 1 of the blog post about Minimal Download Strategy and javascript adjustments for user code. What I initially thought should be enough for one post, is not enough, so I see it as a part 1. I wrote this post after I had read Chris O’Brien’s post about JSLink Here I want investigate how we can get his accordion list view working with MDS. Minimal Dowload Strategy or MDS is a new feature in SharePoint 2013. By now, if you read this post, you already know about it. The simplest way to see if MDS is enabled on your site, you can recognize it on the “ugly” urls. I don’t think they are so ugly. But it is a matter of taste and habit. No matter if you like MDS or not, MDS is enabled on many site templates and is a huge step towards a faster, more responsive architecture in SharePoint, I would say, towards the Single Page Application concept in SharePoint (but it is a long way to go). We have to keep the MDS in mind, when we write our customizations in javascript. SharePoint 2013 loves javascript and the probability is high that you write a lot of javascript. If it doesn’t work with MDS, your code breaks and the user doesn’t see the functionality, or the site owner must disable the Minimal Download Strategy feature. I wouldn’t like to have disabling of an improvement feature as a prerequisite for my code. In this blog post I want to dig into the techniques for getting the javascript code working with MDS. For a while ago I read a wonderful blog post in Chris O’Brien’s blog:

Do an unsafe update in a unified manner « Sharepoint. Kunskap. Upptäckter på resan. - Sep 3, 2011

[…] Log class is my own class which I presented in my previous post. Like this:GillaBli först att gilla denna […]

Here is a simple log which has been inspired of Android Log. It logs to ULS which you can open with ULSViewer, SharePoint Log Viewer.

using System;
using Microsoft.SharePoint.Administration;

namespace Contoso.Intranet.Portal.Utilities
{
    public class Log
    {
        private static readonly string \_CATEGORYNAME = "CONTOSO";
        private static readonly SPDiagnosticsCategory \_ERROR\_CATEGORY = 
              new SPDiagnosticsCategory(\_CATEGORYNAME, TraceSeverity.Unexpected, EventSeverity.Error);
        private static readonly SPDiagnosticsCategory \_WARNING\_CATEGORY = 
              new SPDiagnosticsCategory(\_CATEGORYNAME, TraceSeverity.High, EventSeverity.Warning);
        private static readonly SPDiagnosticsCategory \_VERBOSE\_CATEGORY = 
              new SPDiagnosticsCategory(\_CATEGORYNAME, TraceSeverity.Verbose, EventSeverity.Verbose);
        private static readonly SPDiagnosticsCategory \_INFO\_CATEGORY = 
              new SPDiagnosticsCategory(\_CATEGORYNAME, TraceSeverity.Medium, EventSeverity.Information);

        private static void WriteTrace(SPDiagnosticsCategory category, string message, string trace)
        {
            SPDiagnosticsService.Local.WriteTrace(0, category, category.DefaultTraceSeverity, message, trace);
        }

        public static void Error(Exception ex)
        {
            WriteTrace(\_ERROR\_CATEGORY, ex.Message, ex.StackTrace);
        }

        public static void Warning(string message)
        {
            WriteTrace(\_WARNING\_CATEGORY, message, "");
        }

        public static void Verbose(string message)
        {
            WriteTrace(\_VERBOSE\_CATEGORY, message, "");
        }

        public static void Info(string message)
        {
            WriteTrace(\_INFO\_CATEGORY, message, "");
        }

    }
}

A possible improvement can be a custom Area. See an example of ThorstenHans on Github: CustomLogger.cs EDIT: I found an interesting article: How to log to the SharePoint ULS Logs: Clean Debugging and Error Logging broken down into steps written by Philip Stathis.